The problems connected with accumulation of foreign material in drive mechanism employed with various types of farm machinery are as old as the technology of farm machinery itself. The problem has been particularly vexing insofar as chain and belt-type sprocket drives are concerned since these types of mechanism are used in applications frequently involving direct exposure to foreign matter such as cuttings, weeds and the like. For example, in a crop harvesting apparatus a set of sprocket-entrained conveyor belts may be employed to gather cuttings such as stalks and transport them to processing stations.
It has been a practice of the prior art to attempt to provide a self-cleaning action for sprocket drives by utilizing a plurality of wiper bars or fingers mounted adjacent to the sprocket gear and extending to a point in close proximity to the sprocket hub whereupon material which becomes wrapped about the hub is stripped away.
A problem with such prior arrangements has been that for a drive comprising a single sprocket gear at least two wiper arms are required, one to clean the hub on each side of the gear. In the case of a drive employing compound sprockets, still additional wiper arms are required to clean the hub sections between the several sprocket gears as well as to clean the hub sections on the outer ends of the gear.
Such multiple wiper arm configurations are bothersome from a replacement and repair standpoint since the support mechanism for the arms tend to be complicated, making it difficult to remove and replace a broken arm, particularly if the broken arm happens to be the center one of a three-arm arrangement. Furthermore, the several arms quite often, of necessity, have different shapes whereupon it becomes necessary to maintain a stock of several different types of replacement parts.
Furthermore, the necessary clearance space required between the sides of the wiper arms and the adjacent sides of the sprocket gear or gears leaves a gap in which thin strands of foreign material such as straw, string and the like can collect and possibly build up to the point of interfering with the rotation of the mechanism.